Glyphosate is a very important herbicide, which inhibits an important enzyme, i.e. 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), for the biosynthesis of aromatic amino acids in plants. Glyphosate is a herbicide with extremely wide spectrum, which is also lethal to crops. Hence, to perform selective weeding during the growth of crops, the crops have to obtain glyphosate resistance.
Glyphosate can inhibit 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) of the biosynthesis of aromatic amino acids in majority of bacteria. However, it has been discovered that, EPSPS of partial bacteria has resistance to glyphosate, and the EPSPS of these bacteria has been obtained by separation. Plants can obtain glyphosate resistance by transgenic expression of resistant EPSPS. The resistance obtained by expression of EPSPS of Agrobacterium (Agrobacterium tumefaciens sp CP4) and Salmonella typhimurium CT7 in plants has already been applied in production (U.S. Pat. Nos. 453,590, 4,769,061 and 5,094,945). However, to raise the resistance level of transgenic crops and increase the diversity of resistant gene, new glyphosate-resistant genes and transgenic glyphosate-resistant plants based thereon are still in demand in application in production.
The EPSPS obtained from Deinococcus radiodurans R1 has high glyphosate resistance (Chinese Patent 200910098129.x). The invention “A glyphosate-resistant gene and application thereof” filed in 2009 under the application No. 200910098129.x provides a glyphosate-resistant gene, wherein the amino acid sequence of the protein encoded by G1174 gene is as shown in SEQ ID NO: 2 in the patent. Although the glyphosate-resistance of EPSPS of D. radiodurans R1 is relative high, it is still very necessary to obtain modified genes of EPSPS with higher resistance. The resistance level conferred to transgenic plants can raise the application dosage of glyphosate, thereby retarding the development of resistant weeds and avoiding hazard caused by dosage problem during the application process.